In oilfield and gas drilling operations, electronic equipment such as pressure probes, directional sensing probes, and the like are typically all located together down-hole in a well-bore and co-axially within one drill pipe of a multi-pipe drill string. The probes each have multiple electrical contacts which require electrical mating connection to be made with a mating electrical connection in an up-well segment of another drill pipe/collar. The up-well drill pipe typically contains additional electronic equipment such as a battery power supply as well as transmitting equipment powered by such battery power supply, for powering such sensors in said down-hole pipe and for powering transmitters for transmitting information received from such sensors via the mating electrical connection up-well to surface receptors and data recorders.
More particularly, in an underground drilling environment, measurement or logging instruments are often employed to provide information regarding the drilling status, performance or environment. This information may be stored in memory or telemetered to surface in real time. The measurement and/or telemetry tools are typically battery or generator powered and both the electronics and batteries are contained in pressure resistant housings mounted concentrically along the central axis of the drill collars forming an annulus within the drill pipe through which high-pressure drilling fluid is passed.
The measurement/telemetry tools of the type described above must withstand extremes of pressure, vibration and temperature. Depending on the combination of measurement/telemetry tools chosen, they may exceed the approximate 30′ length of standard drill pipe/collars, or specific sensors may be rigidly fixed to shorter sections of modified drill collars. In this case, electrical tools must span more than one drill collar. Difficulty occurs with the need to simultaneously mate and unmate both the drill collars and the internal electrical housings, yet do so in a manner in which the electrical connections are shielded from the environment to not only protect the electrical connections from a corrosive, potentially explosive, and/or wet environment which would be detrimental to establishing electrical connection, but also from physical damage or deformation to the electrical connectors during the mating and un-mating connection of drill strings and the associate required mating and un-mating connection of electrical connectors axially situate within respective adjacent drill pipe/collars.
In addition, a further problem arises where mating connection between co-axial male plug and mating female socket connections are required to establish such electrical connection. In particular, where electrical connection is required between a coaxial male plug, having multiple circumferential spaced apart electrical contacts thereon, and a female socket connector having a mating diameter and a corresponding number of electrical contacts thereon. Specifically, the procedure of engaging a male plug having a plurality of circumferential electrical connections thereon within a coaxial female socket aperture so as to form the electrical connection with the multiple electrical contacts thereon will cause many of the contacts in the male plug to “wipe” past those of the female socket during insertion, generally in an electrically inappropriate manner, that may damage the electronic circuits associated with such contacts before the contacts are each fully and appropriately engaged with the responding electrical contact. In addition, a further problem arises in that the preferred method of making such electrical connections is typically to insert by rotationally screwing one tubular housing containing the male plug into a similar tubular housing containing the female socket. The environment in which this occurs could also be hazardous—for instance, on the floor of an oil-drilling rig where flammable gases may be present. In such circumstances it is advisable to make certain that no potentially live electrical contacts are capable of causing a spark or thermal effect that could ignite flammable gas, dust or vapor during rotatable insertion of the male plug into the female socket.
Accordingly, a means and apparatus to allow for the joining of the internal electrical connections is desired, and in particular in a down-hole drilling application to allow electrical connection between electronic componentry located in two or more separable drill pipes to be accomplished.
Referencing U.S. Pat. Nos. 6,123,561, 6,392,317, and 5,334,801, prior methods for drill collar electrical connections have included electrical connectors integral to the drill collars. This arrangement requires specialized drill collars, and makes required recutting of the mating threads an additional step and expense, and also requires a method to transfer the electrical leads back and forth between drill collars and internal electrical components.
Additional patents such as U.S. Pat. Nos. 5,389,003, 6,439,932, and 5,358,418 teach a class of connectors referred to as “wet connects”. These connectors, while primarily employed to make electrical connections downhole between a wireline cable and probe, have also been employed in an attempt to make interconnections between probes mounted in drill collars. The art is not well suited for this application, as the wet connects tend to be elongated to the point that they extend out of the drill collar connections, making them subject to damage. Further, the unconnected contacts are generally exposed, and this makes safety a concern in hazardous environments, where the exposed contacts could create a spark.